Microscopy Techniques for Analysis of Nickel Metal Hydride Batteries Constituents

With the need for improvements in the performance of rechargeable batteries has come the necessity to better characterize cell electrodes and their component materials. Electron microscopy has been shown to reveal many important features of microstructure that are becoming increasingly important for understanding the behavior of the components during the many charge/discharge cycles required in modern applications. The aim of this paper is to present an overview of how the full suite of techniques available using transmission electron microscopy (TEM) and scanning transmission electron microscopy was applied to the case of materials for the positive electrode in nickel metal hydride rechargeable battery electrodes. Embedding and sectioning of battery-grade powders with an ultramicrotome was used to produce specimens that could be readily characterized by TEM. Complete electrodes were embedded after drying, and also after dehydration from the original wet state, for examination by optical microscopy and using focused ion beam techniques. Results of these studies are summarized to illustrate the significance of the microstructural information obtained.